The present invention relates to a fluid reservoir with means for sensing the level of liquid within the reservoir, especially for use in master brake cylinders.
Many conventional brake fluid reservoirs have fluid-level sensors which include a magnet mounted on a float floating on the brake fluid within the reservoir. The magnetic force produced by the magnet acts on a reed switch which senses the position of the float, thereby sensing the amount of fluid present in the reservoir. Some reservoirs further include a check mechanism in which the float is pressed into the brake fluid against the buoyancy of the brake fluid to the position where the reed switch is actuated by the magnet mounted on the float in order to check whether the reed switch is exactly actuated. One conventional fluid level sensor is mounted as a unit on the lid of a fluid reservoir or in the reservoir body. However, this type of reservoir is relatively large and must include many components so that mass production of this reservoir is inefficient and relatively expensive. Recently, in order to improve the manufacturing efficiency by simplifying the configuration of reservoirs, the reed switch of the fluid level sensor has been installed at the bottom of the reservoir to sense a magnet mounted on the bottom of float. The check mechanism of the sensor includes a rod which is capable of pressing the float to the bottom of the reservoir through the reservoir lid and the filter. Since the rod is relatively long and extends through the filter mounted on the reservoir body from the lid, however, the rod is apt to be broken or bent when the lid is removed from or returned to the reservoir. Furthermore, in the case where the float and the filter abut, the filter is securely fixed to the reservoir body in order to prevent excess upward displacement of the filter due to the buoyancy of the float. Thus, the rod is even more likely to be damaged when the lid is moved.